The really odd thing here is that I can't seem to find anything BROKEN in terms of apps/servelets. All the example jsp/servlets seem to be working fine, as does an in-house developed app. However there's a new issue, one that I do not believe is related to this error, but I've been asked to track down the source and fix it.

So what should I be looking for here? (I'm a system admin type, not a developer so my Tomcat/JSP knowledge is generally weak.)

The mod_jk files are up to date, and I'm using the correct binaries for the correct version of Apache HTTP on each system. The few posts on the site seem to indicate that this is a case of an AJP port getting input not in AJP format, but I'm not sure what would be doing that. I can make the following error occur simply by telneting to port 8009 (AJP 1.3 connector port) and typing random characters, but note that the "signature ####" is different when I do that:

That number seems to be dependent on the characters I type at the telnet prompt, as I seem to be able to generate the 18245 number if what I type on the telnet line is "GET" (case sensitive as "get" generates a 26469.)

So it seems like there is something that is doing an awful lot of GET requests on this port. Is there a likely culprit?